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  <div class="titlepage"><div><div><h1 style="clear: both">Result returning constructors</h1></div></div></div>
<p>An oft-asked question during conference talks on Expected/Outcome is how to
exclusively use <code>result</code> to implement constructor failure. This is asked because
whilst almost every member function in a class can return a <code>result</code>, constructors
do not return values and thus cannot return a <code>result</code>. The implication is
that one cannot avoid throwing C++ exceptions to abort a construction.</p>

<p>As with most things in C++, one can achieve zero-exception-throw object
construction using a lot of
extra typing of boilerplate, and a little bit of simple C++ metaprogramming. This section
shows you how to implement these for those who are absolutely adverse to ever throwing an exception,
or cannot because C++ exceptions have been globally disabled.</p>

<p>The technique described here is not suitable for non-copyable and non-movable
types. There is also an assumption that moving your type is cheap.</p>



        </div><p><small>Last revised: June 24, 2019 at 21:48:18 &#43;0100</small></p>
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